前车之鉴

nǐ yīng dāng bǎ tā zuò wéi qián chē zhī jiàn

你应当把她作为前车之鉴。

You should take warning from her example.

tā men shì yàn shī bài duì wǒ men shì qián chē zhī jiàn

他们试验失败对我们是前车之鉴。

The failure of their experiment should be a warning to us.